This study is designed to evaluate the effect of Koate-R-HP on the bleeding time of von Willebrand's patients and to evaluate it's effect on other coagulation parameters. Von Willebrand's disease is a bleeding disorder characterized by 1) a deficiency of Factor VIII and 2) a prolonged bleeding time. It is estimated that it is one of the most common inherited bleeding disorders along with hemophilia A and B. Patients will be identified from the coagulation clinic.